In a large stock pot, heat the butter and add garlic and onion. Saute until onion is clear. Add the tomatoes and paprika bring to a heavy simmer, turn down heat, cover, and simmer for 15 minutes. Add the vegetable stock, cover, and simmer for 45 minutes. Strain the soup into another pot and force through a sieve Discard the solids.
Return the soup to a simmer. In a small bowl combine the sour cream and the flour, mixing thoroughly. Whip this mixture into the soup until it's smooth and lump free. Simmer uncovered for 15 minutes to reduce and thicken a bit. Add salt and pepper. When ready to serve, add the vodka and serve immediately.